1. Technical Field
The invention relates generally to pneumatic apparatus for conveying particulate material. More specifically, the invention relates to an apparatus for feeding material to a pipeline from a supply and a control system for maintaining continuous duty operation.
2. Discussion of the Related Art
A pneumatic conveying apparatus for transporting pulverulent, powdery, granular, liquid or like material and products is described in U.S. Pat. No. 4,111,492, issued to Mraz, and such disclosure is fully incorporated herein by reference. The apparatus generally includes a pair of tanks each having a product receiving conduit at the upper end thereof. Door-like valve members are provided to open and close respective upper and lower openings for feeding product into and out of the tanks. A Y-shaped housing provides a dual channel arrangement for separately feeding the product from each tank into the pipeline via a venturi assembly. The product is fed to the pipeline by alternately pressurizing the tanks, one tank filling while the other tank empties.
While the pneumatic conveying apparatus shown in the referenced letters patent is a substantial advance in the art, there are limitations because a technician operating the apparatus must closely watch and inspect the machine to verify safe and proper operation. In particular, it is important to ascertain that the tanks are properly emptying and filling, that the venturi assembly receives a continuous, steady, and controlled flow of material without disturbing or degrading the air flow in the venturi, and that there is not a blockage in the system, especially of one or more of the numerous valves. Also, the door-like valve members have been found to exhibit fatigue over extended operating periods, resulting in degraded seal integrity.